From a Wall Street Journal review by Christoph Irmscher of the book by Rebecca Heisman titled “Flight Paths: How a Passionate and Quirky Group of Passionate Scientists Solved the Mystery of Bird Migration”:
Birds, like humans, follow the rhythm of the seasons. Yet as the nights grow longer and the leaves begin to turn, many of them take off, reminding us that what is home for us was, to them, just a place to raise the kids. The questions that puzzled generations of observers—where these birds went, what they did there, why some migrated and others did not—have mostly been answered by modern science, as Rebecca Heisman’s illuminating new book “Flight Paths” suggests. But the mystique remains.
Through the centuries, armchair naturalists have come up with a host of theories about avian travel, one-upping each other in inventiveness. Aristotle didn’t dream up half the wacky ideas on migration still attributed to him, but he did suggest that swallows had been found hibernating in holes, “quite denuded of their feathers,” a claim that triggered further speculations by other writers. Attempting to lay such matters to rest, the Rev. Charles Morton peremptorily stated, in a 17th-century treatise, that there was a very simple reason so many birds weren’t to be seen in the winter: They went to the moon! Morton was oddly specific about their journey, too, calculating that, at the speed of 125 miles an hour, it would take these birds 60 days to get there.
Facts gradually replaced such fantasies, with some help involuntarily rendered by an unhappy stork that landed in northern Germany in 1822 with a giant African spear rammed through its neck, a hard-to-miss clue as to where it had been. Since then, much ingenuity has gone into mapping migratory traffic in the skies, from night-call recordings and telescope sightings to data gleaned from radar readings, satellite telemetry, geolocation and the extraction of isotopes and DNA. Ms. Heisman, a 30-something science writer based in eastern Washington, devotes each chapter of her book to a different method of measuring migration. But she is clear-eyed, too, about the possible harms human curiosity can impose on its subjects. Birds probably don’t enjoy being captured and recaptured, and who are we to say that lugging transmitters the size of little backpacks across an ocean or two doesn’t bother them? “Flight Paths” is accompanied by a parade of close-ups showing compliant little birds (warblers, soras, a spoon-billed sandpiper) tagged or about to get tagged, cradled by Gulliver-like hands. By contrast, the Magellanic penguin, a device tacked to its lower back, looks, well, hopping mad.
Yet the rewards of our desire to have “eyes in the sky” are considerable, even for the birds themselves. For example, so-called “genoscapes,” based on DNA harvested from feathers, allow researchers to keep track of genetically distinct bird populations and thus determine where and when they are most at risk—a measurement that may help stem the staggering tide of avian losses, nearly three billion since 1970 in North America alone.
Ms. Heisman writes to inform, not to impress. Mixing scientific description with relaxed folksiness, she readily admits that she had to look up the word “manqué” (as in “inventor manqué”). Quoting a colleague, she refers to the North American Breeding Bird Survey as “the Dow Jones of the bird world.” And even though she remains mostly mum about her personal life (references to a recent bout with cancer crop up and disappear), she easily wins the reader’s heart, especially when she wittily downplays her own ornithological credentials. Thus, we see her in her driveway trying her hand at “moon watching,” hoping to catch flocks of migrating birds passing across the moon’s disk. A technique pioneered in the 1940s by veteran ornithologist George “Doc” Lowery and adopted by bird enthusiasts across the nation, such lunar revelations yielded enough information to produce a continent-wide view of migration patterns. But Ms. Heisman is no Doc Lowery: All she can see, after dragging her telescope farther and farther down the driveway, is a small black dot traveling over the moon’s surface—it might have been her favorite bird, the lazuli bunting back from Mexico. Or maybe it was just a bug.
In Ms. Heisman’s book, such stories of opportunities nearly missed lighten what could have turned into a dry celebration of scientific progress. In fact, migratory tracking began modestly. In 1804, the young French-American naturalist John James Audubon looped small pieces of silver thread around the legs of a few eastern phoebes nesting near his father’s estate of Mill Grove, Pa. To his delight he spotted some of them again a year later, freshly returned from their southern haunts. But did he really? Ms. Heisman suggests that Audubon made the story up since he would have been abroad when he said the birds came back. But Audubon wrote about his experience 30 years later—surely he can be forgiven for being a year or two off?
Audubon’s homegrown example created a pattern for future and more ambitious endeavors, which all followed a similar storyline: Intrepid MacGyver-like bird devotee cooks up device and then tries it out, forsaking career, money, family, and personal safety. The king of such ornithological derring-do was Bill Cochran, an electrical engineer by training, who, piloting his own plane in pursuit of radio-tagged birds, ended up in such mid-air trouble that he radioed in his will. In 1973, Cochran glued one of his transmitters to a Swainson’s thrush, a shy, brownish bird smaller than a robin, and then, driving a truck with a huge antenna poking through the roof, followed it for 930 miles through several states and into Canada. Swainson’s are nocturnal migrants, so Cochran and his sidekick Charles Welling took to snoozing during the day and traveling at night, which didn’t prevent them from getting into all sorts of scrapes, including (for Welling) a spell in jail. Over Manitoba, the signal—and, of course, the thrush—disappeared. The result of the men’s adventure: a three-page paper in a scientific journal. Ms. Heisman’s book tells the story the article didn’t, in prose so vivid that it puts us right into Cochran’s truck, the “beep . . . beep . . . beep” of the transmitter piercing the night as the headlights flicker across the highway ahead.
Satisfyingly, after so much technical detail, the final chapter of “Flight Paths” returns to what’s always been at the heart of ornithology—close observations in the field. Going birdwatching at a nearby lake, alerted by unfamiliar calls, Ms. Heisman watches a flock of tundra swans assembling on the water and then lifting off, their wings beating noisily as they head north again.
“Flight Paths” does what only the best science books do: It adds to our knowledge of the world without diminishing its wonder. To think that at night, as we rest in our beds, a nation of winged creatures “of all shapes and sizes” is on the move above us, that a tiny bird like the blackpoll warbler, weighing less than a pencil stub, has seen more of this planet than most of us ever will! And how about those bar-headed geese winging their way across the Himalayas, through the “thin air at the roof of the world,” ascending more than 20,000 feet in just eight hours? The book’s real heroes are not the scientists but the birds
Christoph Irmscher is the author of “The Poetics of Natural History”
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